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.TH SCHED_SETPARAM 3C "Apr 1, 2008"
.SH NAME
sched_setparam \- set scheduling parameters
.SH SYNOPSIS
.LP
.nf
#include <sched.h>

\fBint\fR \fBsched_setparam\fR(\fBpid_t\fR \fIpid\fR, \fBconst struct sched_param *\fR\fIparam\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBsched_setparam()\fR function sets the scheduling parameters of the
process specified by \fIpid\fR to the values specified by the \fBsched_param\fR
structure pointed to by \fIparam\fR. The value of the \fIsched_priority\fR
member in the \fBsched_param\fR structure is any integer within the inclusive
priority range for the current scheduling policy of the process specified by
\fIpid\fR. Higher numerical values for the priority represent higher
priorities. If the value of \fIpid\fR is negative, the behavior of the
\fBsched_setparam()\fR function is unspecified.
.sp
.LP
If a process specified by \fIpid\fR exists and if the calling process has
permission, the scheduling parameters will be set for the process whose process
\fBID\fR is equal to \fIpid\fR. The real or effective user \fBID\fR of the
calling process must match the  real or saved (from \fBexec\fR(2)) user
\fBID\fR of the target process unless the effective user \fBID\fR of the
calling process is \fB0\fR. See \fBIntro\fR(2).
.sp
.LP
If \fIpid\fR is zero, the scheduling parameters will be set for the calling
process.
.sp
.LP
The target process, whether it is running or not running, resumes execution
after all other runnable processes of equal or greater priority have been
scheduled to run.
.sp
.LP
If the priority of the process specified by the \fIpid\fR argument is set
higher than that of the lowest priority running process and if the specified
process is ready to run, the process specified by the \fIpid\fR argument
preempts a lowest priority running process. Similarly, if the process calling
\fBsched_setparam()\fR sets its own priority lower than that of one or more
other non-empty process lists, then the process that is the head of the highest
priority list also preempts the calling process. Thus, in either case, the
originating process might not receive notification of the completion of the
requested priority change until the higher priority process has executed.
.SH RETURN VALUES
.sp
.LP
If successful, the \fBsched_setparam()\fR function returns \fB0\fR.
.sp
.LP
If the call to \fBsched_setparam()\fR is unsuccessful, the priority remains
unchanged, and the function returns \fB\(mi1\fR and sets \fBerrno\fR to
indicate the error.
.SH ERRORS
.sp
.LP
The \fBsched_setparam()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
One or more of the requested scheduling parameters is outside the range defined
for the scheduling policy of the specified \fIpid\fR.
.RE

.sp
.ne 2
.na
\fB\fBEPERM\fR\fR
.ad
.RS 10n
The requesting process does not have permission to set the scheduling
parameters for the specified process, or does not have the appropriate
privilege to invoke \fBsched_setparam()\fR.
.RE

.sp
.ne 2
.na
\fB\fBESRCH\fR\fR
.ad
.RS 10n
No process can be found corresponding to that specified by \fIpid\fR.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	MT-Safe
_
Standard	See \fBstandards\fR(7).
.TE

.SH SEE ALSO
.sp
.LP
.BR Intro (2),
.BR exec (2),
.BR sched_getparam (3C),
.BR sched_getscheduler (3C),
.BR sched_setscheduler (3C),
.BR sched.h (3HEAD),
.BR librt (3LIB),
.BR attributes (7),
.BR standards (7)
